This invention relates generally to method and apparatus for converting energy in a two-phase (liquid and gas) fluid jet into mechanical power, as for example is delivered by a rotating turbine shaft. The liquid and gas may be two separate chemical components or may be the vapor and liquid phase of a single chemical component.
In the past, turbine equipment has been built to handle conversion of gas-phase energy or liquid-phase energy into shaft power. Other approaches have been attempted to convert the energy of both phases; however, problems then developed, including erosion, corrosion, and/or considerably lower efficiency. For example, a rotating separator has been employed to separate the liquid phase for conversion of kinetic energy of that phase into useful shaft power. However, the kinetic energy of the gas phase was dissipated.
In another example, a separator was not used, and the two-phase jet was directly impinged on moving turbine blades. Here again, kinetic energy of the gas phase was undesirably dissipated, and for high jet velocities, enhanced corrosion and erosion of the blades tended to occur.
Flash geothermal systems and some other processes dissipate the energy of two-phase flow, separate the gas, and then pass the gas through a gas-phase turbine. This approach wastes most of the available energy of the two-phase flow. (In a single component, two-phase system, such as steam and water, the dissipated energy makes heat which produces additional gas, which can produce some additional power in the gas-phase turbine; however, it is much less than the available energy of the two-phase flow.) This process wastes available energy in the two-phase flow.
There is need for improved means to convert both the gas energy and the liquid energy in a two-phase flow to useful power, whereby a considerable improvement in efficiency can be realized. For example, if the two-phase flow from a typical geothermal well is flashed and the steam is separated and used in a steam turbine, a total of 12,951 kW would be generated. If a suitable two-phase device is used to convert the liquid kinetic energy resulting from a two-phase expansion, a total of 15,014 kW would be generated by the device and a steam turbine, yielding a power increase of 16%.